The World Interoperability for Microwave Access Forum (Wimax Forum) is a non-profit organization consisting of leading system equipment manufacturers, component (including chips, RFs, antennae, and so on) suppliers, software suppliers and service suppliers, and has successively established a certification working group (CWG), a technical working group (TWG), a spectrum working group (RWG), a market working group (MWG), a requirements working group (SPWG), a network working group (NWG) and an application working group (AWG).
The NWG makes and researches the Wimax network architecture specification, and the work is divided into three stages of release versions as desired by the developing process. So far, Release1.0.0 has been issued, and the version is further divided into the following three stages: Stage1 is carried out in the SPWG, and the objective is to define requirements for functions and performances of the network in nomadic, portable, simple moving and all mobile modes; Stage2 and Stage3 are carried out in the NWG, and the task of Stage2 is to make a network architecture reference model, define reference points and network functions, and give interpretations of the protocol and flow; Stage3 is to refine the implementation of the protocol and flow on the basis of Stage2.
FIG. 1 illustrates the Wimax network architecture reference model, and FIG. 2 and FIG. 3 depict a functional decomposition model of an access service network (ASN).
The model in FIG. 1 is a network reference model based on 802.16. The reference model consists of three logical entities: a mobile station (MS)/stable station (SS), an access service network (ASN) and a connection service network (CSN), and the logical entities connects with one another via standard reference points (RP) R1 to R5. Each logical entity represents a group of functional entities, and each function can be implemented in a single physical device or in distributed multiple physical devices.
The reference points will be described in detail below:
Reference point R1: this reference point is an interface between the SS/MS and the ASN, and is consistent with the physical layer and MAC layer of the IEEE 802.16e-2005 or IEEE 802.16d-2004 air interface, moreover, the reference point R1 may also comprise an additional protocol of management plane;
Reference point R2: this reference point is a logical interface between the SS/MS and the CSN, and it is established on the physical connection between the SS/MS and the CSN, for authentication, service authorization, IP host configuration management, and so on. Wherein, the authentication function of the reference point R2 is performed between the mobile station (MS) and the CSN of the home network service provider (H-NSP), and under a roaming mode, the ASN and the CSN of the visited network service provider (V-NSP) can also process part of the authentication flow and mechanism; the IP host configuration management can be performed between the MS and the NSP of the home place or the CSN of the visited place;
Reference point R3: this reference point is an interoperability interface between the ASN and the CSN, comprises a series of protocols of control and bearer plane, and supports AAA, policy enforcement and mobility management. In addition, the reference point R3 may also comprise a method, such as tunnel establishment, for bearer plane data transmission between the ASN and the CSN;
Reference point R4: this reference point consists of a series of control and management plane protocols initiated and terminated inside the ASN, and is used to implement functions associated with the MS mobility coordination between multiple ASNs and an access network gateway (ASN-GW), moreover, the reference point R6 inside the ASN (see FIG. 2) can also implement the same functions;
Reference point R5: this reference point consists of a series of control and bearer plane protocols for the interoperability between the visited CSN and the home CSN;
Reference point R6: description of the reference point R4 can be referred to.
The ASN administrates an IEEE 802.16 air interface and provides wireless access for WiMAX users. The ASN consists of at least one BS and one ASN gateway (GW), and it may comprise a single ASN-GW or multiple ASN-GWs. FIG. 2 and FIG. 3 respectively illustrates an ASN reference model with a single ASN-GW and an ASN reference model with multiple ASN-GWs.
In FIG. 3, ASN connects with the MS at the reference point R1, connects with the CSN at the reference point R3, and connects with another ASN at the reference point R4. The reference point R4 is a unique reference point connecting ASNs of identical or different ASN Profiles on control and bearer planes. Different types of ASNs can connect with the original ASN via specific protocols on R1, R3 and R4. If an ASN consists of n (n>1) ASN-GWs (as illustrated in FIG. 3), the mobility inside the ASN relates to establishment of control messages and a bearer plane of R4. For all application protocols and flows, the reference point R4 inside the ASN should be completely compatible with the reference point R4 between ASNs.
The base station is a logical entity, and a base station instance can implement the MAC and physical layers specified in IEEE 802.16 standards. A base station instance represents a sector operating on a frequency, and it comprises uplink and downlink scheduling functions, implementation of which depends on the equipment manufacturer and is without the scope of the network architecture specification. With regard to load balancing and redundancy, a single BS may be required to connect to more than one ASN-GW (that is, the case illustrated in FIG. 3, in which reachability of the above ASN-GWs can be achieved).
The ASN-GW is also a logical entity and represents a set of control plane functional entities, and these functions may have peers of corresponding functions (such as functions in the CSN in the BS instance or functions in another ASN) in the ASN (such as paging controller, authenticator, which will be described below, data path function (DPF), and so on). In addition, the ASN-GW can also perform bearer plane routing or network bridge function.
The components will be described in detail below.
Authenticator: the authenticator has its definition in each standard EAP three party model. The authenticator, located at one end of a point-to-point link, is a unit helping a MS to connect to the other end for authentication. Before permitting a terminal to access a service, the authenticator performs compulsory authentication. The authenticator can also comprise an AAA client communicating with a certification server based on AAA and providing authentication service for the authenticator via the AAA protocol. Generally, the authenticator is located at the same location as a key distribution device, or may be located at the same location as an authentication relay and a key reception function. In this disclosure, the authenticator, as a functional entity of an ASN-GW, resides in the ASN-GW.
Paging controller (PC): the paging controller is a functional entity administrating acts of MSs under the idle mode in a network. In IEEE802.16e, it is identified by a 6-byte PC ID which can be mapped to the address of the functional entity inside an NWG. In this regard, the paging controller (PC) can either reside in a BS (without the consideration of NWG) or separate from the BS and reside in an ASN-GW via the reference point R6.
At present, there are mainly two types of paging controllers:                Anchor PC: for each MS in the idle mode, there must be a PC (the Anchor PC) comprising location information of the MS.        Relay PC: in the network, there may also be one or more PCs (Relay PC) which transmit paging or location management messages between the BS of the PA (Paging Area) and the anchor PC.        
The NWG Stage2/Stage3 protocol defines MS operation functions in paging and idle modes, and the functions require consistency with the relevant functions in IEEE 802.16e. The idle mode is mainly for an MS to decrease its power consumption to prolong its working hours in the case that there is no service being processed, and in the idle mode, the MS is not registered on a specific BS, and it can access the network by paging and location update in a paging interval.
An idle mode timer is defined in IEEE 802.16e, and an MS must initiate a location update before the timer expires, and after the location update is completed, the MS and the network side will both reset the timer, and if there is no location update initiated when the timer expires, the network side considers that the MS is not in the network and releases all the resources associated with the MS, and the MS should also consider that the network side no longer has a context associated with it. Therefore, the location update flow can be considered as a method for the network side to periodically detect whether an MS in the idle mode is still in the current Wimax network.
In the Wimax network architecture, the location update flow is part of the paging controller functional entity management (the scenario in which a paging controller and a BS are combined is without the consideration of this disclosure as well as the scope defined by NWG, and is within the scope defined by IEEE 802.16e), what is considered in this disclosure is a scenario in which a paging controller resides in an access service network gateway entity, and in this scenario, the paging controller interacts with a paging agent (a functional entity residing in a BS to implement the paging function defined in IEEE 802.16e and to interact with a PC via R6 interface or an inner interface) to implement relevant message interchange, and messages between paging controllers are interchanged via the reference point R4.
However, neither behaviors related to the idle mode timer nor description related to the periodical location update is defined in the standard flows and messages of the NWG Stage2 and Stage3 protocols. Besides, there is no relevant solution proposed to date.